As I am getting back to the gym and really trying to go for some size I am changing from a 2day on, 1 day off, 2 day on routine to a FBW 3 times a week to help fit around my new schedule.

So far to start I plan to do the same workout each day (mon, wed, fri/sat), but change the order of exercises. I will after a few weeks change to do:

Workout A
Workout B
Workout A

I plan to do 4 sets of 6-8 reps, with the focus being on gaining size over anything else. I especially want to add size to my chest and shoulders, but obviously don't want to neglect other bodyparts:

here is the workout:

Bench Press - Chest
Dumbell Flys (On a flat bench) - Chest
Hanging Leg Raises - Abs
Tricep Pull Down (Rope, standing) - Triceps
Squats/Hack Squats - Legs
Bent over dumbell row - Back
Upright Dumbell Row - Shoulders
Dumbell Curls on Incline Bench - Biceps

Is that enough exercises to do 4 sets of 6 -8 reps,
Or would I be better to just do 3 sets of 6-8 reps???

Also I was thinking of changing the bent over dumbell row to pull ups for my back?

If you have any suggestions please post them. As far as I am aware 6-8 reps should be the optimum for gaining size?

As I say I want to try and get as much size on my chest as I can and improve my delts and general shoulder area more than anything.

I am coupling this with a clean bulk and not very much cardio. After christmas I will start with cardio though and do some running etc.

Thought you said there are 2 workouts, i see one.

FWIW, take a look at this little writeup on the leg raises:

Fat Loss & Weight Training Myths

I do them as well, but as an ab excercise, it looks like it's not really doing what most people think. Might want to add crunches or planks to the routine.

I haven't got two workouts yet, but I am going to start out with just the one for now, say for 2 weeks, then go for an A.B,A type schedule.

I've quickly skimmed over that link and will take a proper look after work but will probably take out the leg raises for something more effective. Is it worth doing isolation for the core or not bother at the moment?

I have seen a good number of people on here suggest it gets worked enough during other lifts and not to bother with them directly until a later date. Is there anything else that people think I should change apart from the leg raises?

Also do I have enough in there for Biceps and Triceps??

truthfully if you are going for 3 Full body workouts a week why limit yourself to doing the same exercises in each session?

So why change the dumbell rows for pull ups, just do them both just on different days also gets some deadlifting in there and probably some good mornings too. Also you could alternate bench with barell bench, incline bench and dumbell bench.

you also have two chest exercises,but only one horizontal pull for back and no vertical pull ie chins,drop the flyes and add chins,or as jsb said alternate routines.